telephone light

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telephone light

Post by myp71 » Tue Sep 23, 2003 11:07 pm

using a neon light I believe a n92 neon . What will I need, to have this neon light when my phone rings a resistor right? What value would I use for this app and this neon is nonpolar right so it doesn't matter what is hot or ground also is this all I need no capacitor or anything just resistor correct ??<p>thanks for your help

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Re: telephone light

Post by dyarker » Wed Sep 24, 2003 4:05 am

If you connect inside the phone, right across the ringer, you only need the Ne lamp and a resistor. (Because the phone already the capacitor in series with the ringer.)<p>On the other hand, to connect across the line you will need a capacitor too. Otherwise, once the ringing voltage strikes the Ne lamp, it may stay on drawing the DC current. The DC voltage will drop below the Ne holding voltage, and the lamp will go out. By the time it does, it MAY have answered and hung up on the caller. NOT WHAT YOU WANT IT TO DO!<p>I don't what specs are on part number n92; try 10K Ohm resistor and a 0.22uF 200V poly or mylar capacitor.<p>OR, two LEDs in parallel with opposite polarity, in series with a 5K Ohm resistor and 1uF 200V poly or mylar capacitor. Try different resistor values to get 15 - 20mA through the LEDs when the phone rings.<p>Cheers,<p>[ September 24, 2003: Message edited by: Dale Y ]</p>
Dale Y

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Re: telephone light

Post by Externet » Wed Sep 24, 2003 11:14 am

Connect the neon bulb in series with a ~33 K Ohm resistor directly across the telco pair. No capacitor is needed, The neon bulb blocks DC itself.
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Re: telephone light

Post by MrAl » Wed Sep 24, 2003 11:40 am

Hello there,<p>Another idea would be to get one of the
super high intensity LED's sold everywhere.<p>Put a common rect diode in parallel with it
along with a resistor in series with the
parallel combination.
The diode cathode should connect to the
anode of the LED.<p>To use, connect this across the line.
If you connect it backwards, the LED will
light as soon as it's connected, so you
will have to reverse it. Once you have it
right, it wont light up until the phone rings.<p>Start with a resistor value of 20k.
This should provide enough current when the
phone rings, but you'll have to make sure you
use a super bright LED, not a plain run of the
mill LED.<p>The super brights are more expensive, from
something like $2 and up, but they come in
many nice colors.<p>Note that a regular LED may not work very well,
but i havent tried it yet. Since your idea
with the neon got me to think about this,
i think ill build one later today if i have
time (with the LED of course).<p>I assume you live in the USA.<p>Take care for now,
LEDs vs Bulbs, LEDs are winning.

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Re: telephone light

Post by myp71 » Wed Sep 24, 2003 12:52 pm

Thanks for the help I will try and see which one I like better. <p>

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Re: telephone light

Post by jollyrgr » Wed Sep 24, 2003 4:12 pm

Put the neon bulb in series with a high Ohm resistor (like Externet suggested). The 33k Ohm resistor will not drop enough DC current to seize the line. If you used the neon light by itself you might have this problem.<p>I have used LEDs in the past. A 5K or 10K resistor should work nicely. Be sure to put two LEDs in parallel in opposite directions. This will prevent the inverse voltage from killing the single LED.
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Re: telephone light

Post by Chris Smith » Wed Sep 24, 2003 6:33 pm

To Extranet, the neon does not block DC, it will ignite with AC or DC, when its conductive voltage is met. USUALLY around 90 volts, but lower voltages can partially ignite the gas. Most DC in phone lines is around 55 volts, ideal, but you never know? Same for Neons, Ive had 65 volts set them off.

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